Degradability of Polymers in Soil

Standardisation working groups are nowadays asked to define the criteria of acceptability of polymers expected to biodegrade in soil. Standardisation is therefore expected to 

Looking at the discussions held lately by the different standardisation working groups and experts, there are two starting points which seem to meet a common consensus and can therefore be considered as a basis on which definitions and test methods can be built on  

Test methods and procedures able to generate reliable, quantitative, and reproducible experimental results shall be used to measure biodegradability. This is important to allow the transparency of the evaluation process and to avoid claims based on qualitative data. 

Criteria and requirements should be formulated so as to prevent the accumulation of man-made materials in soil, and ecotoxic effects. 

The former starting point is a typical requirement of standardisation, which aims at unifying methods. The latter is a social need, because it is based on the requirements set by the different stakeholders involved in the use of biodegradable plastics in soil, namely the farmers, the public authority and public opinion. 

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A large wealth of literature is available for biological degradation of polymers in soil or compost, whereas little information is available on the degradation processes in aqueous environments. Since the applications of polymers in contact with aqueous environments are now gaining popularity, biodegradation under aqueous conditions becomes a matter of concern. The durability and lifetime of polymers certainly depends on the water body composition wherein they are used (seawater, freshwater, etc.) and also on the availability of methods that can detect the level of degradation in such conditions. 

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